Just an fyi.
Just thought I'd add this on here in case it's of help. It is from 2003, so is not that recent but it discusses possible secondary causes of CPTH
http://www.hacoop.org/professionals_5_1.html
Chronic Post-Traumatic Headache (2003)
Thomas N. Ward, MD and Morris Levin, MD
Co-Directors, Dartmouth Headache Center
Lebanon, New Hampshire